Evaluation of mouthpiece fixation devices for head and neck radiotherapy patients fabricated in PolyJet photopolymer by a 3D printer

•Modeling mouthpiece for radiotherapy using a 3D printer.•Revealed accurate modeling with a 3D printer.•Elucidating the process of creating appropriate STL 3D images.•Usefulness of dose distribution of MED610 mouthpieces. The purpose of our study was to evaluate the usefulness of a biocompatible class VI resin PolyJet photopolymer Objet MED610 (MED610)-made mouthpiece fabricated using a 3D printer as a fixation device for head and neck radiotherapy patients. Five mouthpieces made of GC Exafine putty type (GCEP) were fabricated from five dry skull bones. After computed tomography reconstruction of the GCEP-made mouthpiece and its surface extraction, the MED610-made mouthpieces were replicated. The sizes of the GCEP and MED610 mouthpieces were measured with a vernier caliper in width, length, and height, respectively. The volumes of these mouthpieces were measured by Archimedes’ principle using pure water. For dose evaluation, the GCEP and MED610 mouthpieces were placed in the same part of a water phantom, and a 4-MV X-ray beam was located at the left maxillary gingiva, buccal mucosa, and oral floor. The dose for the planning target volume (PTV) was evaluated. The differences in the mean size and volume between the GCEP and MED610 mouthpieces were 0.03 mm and 0.21 cm3, respectively. Compared with the conventional GCEP mouthpiece, the dose absorption in the MED610 mouthpiece was closer to that in only water. When the mouthpiece was within the PTV margin, the minimum coverage dose at 95% of the PTV increased by 2.4% in the maxillary gingiva and by 3.6% in the buccal mucosa. A 3D printer can construct a mouthpiece accurately. The MED610 mouthpiece is suitable for use in dosimetry in head and neck radiotherapy.